Safe Haskell	None
Language	Haskell2010

FastString

Contents

ByteString
FastZString
FastStrings
LitStrings

Description

There are two principal string types used internally by GHC:

FastString

A compact, hash-consed, representation of character strings.
Comparison is O(1), and you can get a Unique from them.
Generated by fsLit.
Turn into SDoc with ftext.

LitString

Just a wrapper for the Addr# of a C string (Ptr CChar).
Practically no operations.
Outputing them is fast.
Generated by sLit.
Turn into SDoc with ptext

Use LitString unless you want the facilities of FastString.

Synopsis

ByteString

fastStringToByteString :: FastString -> ByteString Source #

mkFastStringByteString :: ByteString -> FastString Source #

Create a FastString from an existing ForeignPtr; the difference between this and mkFastStringBytes is that we don't have to copy the bytes if the string is new to the table.

fastZStringToByteString :: FastZString -> ByteString Source #

unsafeMkByteString :: String -> ByteString Source #

hashByteString :: ByteString -> Int Source #

FastZString

data FastZString Source #

Instances

NFData FastZString #
Methods rnf :: FastZString -> () Source #

hPutFZS :: Handle -> FastZString -> IO () Source #

zString :: FastZString -> String Source #

lengthFZS :: FastZString -> Int Source #

FastStrings

data FastString Source #

A FastString is an array of bytes, hashed to support fast O(1) comparison. It is also associated with a character encoding, so that we know how to convert a FastString to the local encoding, or to the Z-encoding used by the compiler internally.

FastStrings support a memoized conversion to the Z-encoding via zEncodeFS.

Constructors

FastString
Fields uniq :: !Int n_chars :: !Int fs_bs :: !ByteString fs_ref :: !(IORef (Maybe FastZString))

Instances

Eq FastString #
Methods (==) :: FastString -> FastString -> Bool # (/=) :: FastString -> FastString -> Bool #
Data FastString #
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> FastString -> c FastString Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c FastString Source # toConstr :: FastString -> Constr Source # dataTypeOf :: FastString -> DataType Source # dataCast1 :: Typeable (* -> ) t => (forall d. Data d => c (t d)) -> Maybe (c FastString) Source # dataCast2 :: Typeable ( -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c FastString) Source # gmapT :: (forall b. Data b => b -> b) -> FastString -> FastString Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> FastString -> r Source # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> FastString -> r Source # gmapQ :: (forall d. Data d => d -> u) -> FastString -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> FastString -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> FastString -> m FastString Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> FastString -> m FastString Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> FastString -> m FastString Source #
Ord FastString #
Methods compare :: FastString -> FastString -> Ordering # (<) :: FastString -> FastString -> Bool # (<=) :: FastString -> FastString -> Bool # (>) :: FastString -> FastString -> Bool # (>=) :: FastString -> FastString -> Bool # max :: FastString -> FastString -> FastString # min :: FastString -> FastString -> FastString #
Show FastString #
Methods showsPrec :: Int -> FastString -> ShowS Source # show :: FastString -> String Source # showList :: [FastString] -> ShowS Source #
Outputable FastString #
Methods ppr :: FastString -> SDoc Source # pprPrec :: Rational -> FastString -> SDoc Source #
Uniquable FastString #
Methods getUnique :: FastString -> Unique Source #
Binary FastString #
Methods put_ :: BinHandle -> FastString -> IO () Source # put :: BinHandle -> FastString -> IO (Bin FastString) Source # get :: BinHandle -> IO FastString Source #

Construction

fsLit :: String -> FastString Source #

mkFastString :: String -> FastString Source #

Creates a UTF-8 encoded FastString from a String

mkFastStringBytes :: Ptr Word8 -> Int -> FastString Source #

mkFastStringByteList :: [Word8] -> FastString Source #

Creates a FastString from a UTF-8 encoded [Word8]

mkFastStringForeignPtr :: Ptr Word8 -> ForeignPtr Word8 -> Int -> IO FastString Source #

Create a FastString from an existing ForeignPtr; the difference between this and mkFastStringBytes is that we don't have to copy the bytes if the string is new to the table.

mkFastString# :: Addr# -> FastString Source #

Deconstruction

unpackFS :: FastString -> String Source #

Unpacks and decodes the FastString

bytesFS :: FastString -> [Word8] Source #

Gives the UTF-8 encoded bytes corresponding to a FastString

Encoding

zEncodeFS :: FastString -> FastZString Source #

Returns a Z-encoded version of a FastString. This might be the original, if it was already Z-encoded. The first time this function is applied to a particular FastString, the results are memoized.